#include <stdio.h>

enum{ BUFFERSIZE = 32};

extern void initialize_data(char *data,size_t size);

void func(const char *file_name){
    char data[BUFFERSIZE];
    char append_data[BUFFERSIZE];
    FILE *file;

    file = fopen(file_name,"a+");
    if (file == NULL){
        /* Handle error */
    }

    initialize_data(append_data,BUFFERSIZE);
    if (fwrite(append_data,BUFFERSIZE,1,file) != BUFFERSIZE){
        /* Handle error */
    }
    if (fseek(file,OL,SEEK_SET) != 0){
        /* Handle error */
    }
    if (fread(data,BUFFERSIZE,1,file) != 0){
        /* Handle there not being data */
    }
    if (fclose(file) == EOF){
        /* Handle error */
    }
}